1. Technical Field
The present invention generally relates to perfluorocyclobutane copolymers and their use as biomedical devices such as contact lenses or intraocular lenses.
2. Description of Related Art
In the field of biomedical devices such as contact lenses, various physical and chemical properties such as, for example, oxygen permeability, wettability, material strength and stability are but a few of the factors that must be carefully balanced in order to provide a useable contact lens. For example, since the cornea receives its oxygen supply exclusively from contact with the atmosphere, good oxygen permeability is a critical characteristic for any contact lens material. Wettability also is important in that, if the lens is not sufficiently wettable, it does not remain lubricated and therefore cannot be worn comfortably in the eye. Accordingly, the optimum contact lens would have at least both excellent oxygen permeability and excellent tear fluid wettability.
Contact lenses made from fluorinated materials have been investigated for a number of years. Such materials can generally be subdivided into two major classes, namely hydrogels and non-hydrogels. Hydrogels can absorb and retain water in an equilibrium state whereas non-hydrogels do not absorb appreciable amounts of water. Regardless of their water content, both hydrogel and non-hydrogel fluorinated contact lenses tend to have relatively hydrophobic, non-wettable surfaces.
By introducing fluorine-containing groups into contact lens polymers, the oxygen permeability can be significantly increased. For example, U.S. Pat. No. 4,996,275 discloses using a mixture of comonomers including the fluorinated compound bis(1,1,1,3,3,3-hexafluoro-2-propyl)itaconate in combination with organosiloxane components. Fluorinating certain polysiloxane materials has been indicated to reduce the accumulation of deposits on contact lenses made from such materials. See, for example, U.S. Pat. Nos. 4,440,918; 4,954,587; 4,990,582; 5,010,141 and 5,079,319. However, fluorinated polymers can suffer from one or more of the following drawbacks: difficult and/or expensive synthetic routes, poor processability, low refractive index, poor wettability, poor optical clarity, poor miscibility with other monomers/reagents and toxicity.
The thermal polymerization products of trifluorovinyl-containing monomers, e.g., bis-trifluorovinyl monomers, to form perfluorocyclobutylene polymers are known. See, e.g., U.S. Pat. Nos. 5,021,602; 5,023,380; 5,037,917; 5,037,918; 5,037,919; 5,066,746; 5,159,036; 5,159,037; 5,159,038, 5,162,468; 5,198,513; 5,210,265; 5,246,782; 5,364,547; 5,364,917 and 5,409,777. U.S. Pat. No. 5,225,515 discloses poly(aromatic ether) polymers or copolymers containing perfluorocyclobutane rings in the polymer backbone. Smith et al., “Perfluorocyclobutane Aromatic Polyethers. Synthesis and Characterization of New Siloxane-Containing Fluoropolymers”, Macromolecules, Volume 29, pp. 852-860 (1996) discloses copolymerization of bis(1,3-[4-(trifluorovinyloxy)phenyl])-1,1,3,3-tetramethyldisiloxane with 1,1,1-tris(4-[trifluorovinyloxy]phenyl)ethane. However, there has been no recognition or appreciation of copolymers containing perfluorocyclobutane rings in the polymer backbone and linkages based on at least two of poly(alkyl ether) groups, polyorganosiloxane groups and poly(perfluorocyclobutane) groups or that such materials can be employed in the manufacture of biomedical devices and particularly contact lens applications.
Accordingly, it would be desirable to provide improved fluorinated materials for use in the manufacturing of biomedical devices for prolonged contact with the body while also being biocompatible.